1. Field of the Invention
The present invention relates to a washing machine, and more particularly to a washing machine having a friction apparatus which not only can uniformly wash articles to be washed, but also can improve the washing efficiency.
2. Prior Arts
As is well known, a washing machine is an appliance for separating dirt from articles to be washed such as clothing by sequentially carrying out various cycles in the order of liquid feeding, washing, rinsing, dehydrating, and draining cycles.
While the above cycles are being executed, dirt contained in the articles separates from the articles by means of friction between a liquid flow and the articles or by means of detergents.
FIG. 5 shows such a conventional washing machine 500.
As shown in FIG. 3, conventional washing machine 500 includes a housing 510. An outer tub 520 for receiving a washing liquid is disposed in housing 510. Enclosed within outer tub 520 is a spin tub 530 formed at its side wall with a plurality of discharging holes 532. Below outer tub 520 but within housing 510, there are provided a motor 540 for generating a driving force, and a gear assembly 550 which transfers the driving force of motor 540 to spin tub 530 or to a pulsator 560 rotatably mounted on a bottom wall of spin tub 530.
While the washing cycle is being carried out, pulsator 560 driven by motor 540 rotates is formed and reverse directions, thereby creating a swirl-shaped liquid flow in spin tub 530. The swirl-shaped liquid flow collides with the articles in spin tub 530, so the articles are washed.
However, is conventional washing machine 500, the swirl-shaped liquid flows generated by pulsator 560 become weak as they reach an upper portion of spin tub 530 due to an interference by the articles. For this reason, when a large amount of articles are placed in spin tub 530, the washing effect at the upper portion of spin tub 530 is reduced. Particularly, articles having light weight are not completely immersed in the washing liquid, but float on the surface of the washing liquid in the direction of the liquid flow. As a result, the articles do not widely collide with the liquid flow, so the dirt contained in the articles is not completely separated from the articles.
In addition, since the detergent permeated in the articles is not completely dissolved in the washing liquid, the articles are not cleanly washed.
In order to solve the above problems, various washing machines have been suggested, but they have presented many problems.
For example, U.S. Pat. No. 5,231,857 issued to Rew et al. discloses a washing machine having a roller type agitator. In Rew's washing machine, the roller type agitator comprises at least one roller rotatably mounted on a rotator by means of a rotation shaft. In a washing operation, articles disposed in a spin tub directly makes contact with the rollers so that the articles are equally washed and so that a good washing effect can be obtained.
However, since the rollers are mounted on the rotator installed at a bottom wall of the spin tub, the rollers cannot make contact with the articles placed at an upper portion of the spin tub, so the washing effect at the upper portion of the spin tub is relatively reduced.